1. Field of the Invention
This invention relates to sealed bearing rotary cone rock bits.
More particularly, this invention relates to precision roller bearings for seal bearing rotary cone rock bits.
2. Description of the Prior Art
Roller bearings for rotary cone rock bits have been in the public domain for many years. Roller bearing "air" bits are typically used in open pit mines where a multiplicity of shallow holes are formed in the earth formations. These types of roller bearing rotary cone bits usually are non-sealed bits that rely on a gaseous fluid to lubricate the bearings and to flush the bearings of debris during use of the bit in a borehole. These types of mining bits utilize cylindrical roller bearings that are loosely confined (large bearing clearances) by bearing races formed between a journal and a rotary cutter cone. These open-type bearings encourage the flushing of detritus from the bearing cage by the gaseous fluid pumped under pressure through a connecting drill string.
Prior art U.S. Pat. Nos. 2,030,442, 3,990,525, 4,255,000, 44,359,113 and 4,386,668 represent rock bits that operate under the foregoing parameters.
Sealed bearing rotary cone rock bits that incorporate cylindrical type roller bearings are typically run in a deep well borehole with drilling fluid or "mud" to move the debris from the borehole bottom to the rig floor.
The following U.S. Pat. Nos. 4,249,781, 4,256,193, 4,263,976 and 4,428,687 teach sealed lubricated roller bearings for rotary cone rock bits.
Still another type of rotary cone rock bit utilizes conical bearings oriented between journals and rotary cones. The conical bearings take both radial and axial loads during operation of the bit in a borehole.
U.S. Pat. No. 4,136,748 teaches an open bearing rotary cone rock bit (air bit) with conical bearings that utilizes a gaseous fluid to lubricate and flush the bearings.
U.S. Pat. No. 4,367,904 teaches a sealed bearing rotary cone rock bit that uses conical bearings that are internally grease lubricated through a closed lube reservoir system.
The prior art does not teach a precision roller bearing having very close fits. The bearing package of the present invention includes highly refined surface finishes that complement extremely hard roller bearing elements fabricated from special bearing metals. A specific lubricant is utilized having lube viscosities that are unique to the bearing combination of the instant invention.